1. Field of the Invention
This invention relates to a highly water-resistant adhesive which firmly adheres to hard tissues of the living body such as teeth and bones, metallic materials, organic polymeric materials, and ceramics. The "adhesive" as used herein not only denotes compositions used to bond adherends to one another but also comprehends compositions which are used to form a highly adhesive coating layer on the surface of adherends such as metallic materials and organic polymeric materials or used to form a highly adhesive filling material for repairing hard tissues of the living body. In other words, by "adhesive" is meant any and all compositions which are applicable for adhesion to a variety of substances including hard tissues of the living body, metallic materials, organic polymeric materials, and ceramics.
2. Description of the Prior Art
A variety of metallic materials, organic polymeric materials, and ceramic materials are in use as restorative dental materials. When in use, they are required to firmly adhere to teeth and to one another. Moreover, they are required to exhibit adhesion under a wet condition in the mouth.
Heretofore, many attempts have been made to use a phosphoric ester compound as an adhesive in dentistry. For example, U.S. Pat. Nos. 4,259,075, 4,259,117, and 4,368,043 disclose that a polymerizable composition containing a vinyl compound having a group of the formula ##STR2## is useful as a dental adhesive. U.S. Pat. No. 4,222,780 also teaches that a polymerizable composition containing a vinyl compound having a group of the formula ##STR3## is useful as a dental adhesive. In fact, some of the compositions defined in these patents have found practical use as a primer to be applied to the wall of a tooth cavity prior to the filling of a tooth cavity. The compositions disclosed in the above-mentioned patents, however, have a drawback that they do not firmly adhere to the tooth unless the surface of the tooth cavity previously undergoes acid etching. In addition, they do not firmly adhere to an Ni--Cr alloy which is a common dental metallic material.
On the other hand, attempts have been made to prepare a dental adhesive from a polymerizable phosphoric ester compound as mentioned below.
(i) U.S. Pat. No. 3,882,600 discloses phosphoryl monofluoride.
(ii) There are shown CH.sub.2 .dbd.CH--PO(CH).sub.2 and CH.sub.2 .dbd.CHC.sub.6 H.sub.4 CH.sub.2 P--O(OH).sub.2 in Journal of Dental Research, Vol. 53, p. 878-888 and Vol. 56, p. 943-952; Chemical Abstract, Vol. 77, p. 290 (66175g); and Japanese Patent Laid-open No. 44152/1976.
(iii) Japanese Patent Laid-open No. 113843/53 discloses a compound of the formula ##STR4## (where R is an organic residue having at least one vinyl group), with one of the two OH groups being neutralized. Said patent exemplifies the following compounds, in which M denotes a metal. ##STR5##
(iv) Japanese Patent Publication No. 49557/1982 teaches methacryloyloxyethane-1,1-disulfonic acid of the formula ##STR6##
None of the compounds set forth above exhibit high adhesive strength (particularly to a metal) when used under a wet condition.
European Patent Application No. 58483 (equivalent to Japanese Patent Laid-open No. 151607/1982) describes a polymerizable monomer having a P--Cl bond or P--Br bond effective as an adhesive component. However, the compounds illustrated in this patent do not provide sufficiently high adhesive strength when applied to teeth and metallic materials.
In the industrial fields, many attempts have been made to use a phosphoric ester compound as an adhesive. For example, they are proposed in U.S. Pat. Nos. 3,754,972, 3,884,864, 3,987,127, 4,001,150, 4,044,044, and 4,223,115; Japanese Patent Laid-open No. 20238/1974, 100596/1975, 125182/1976, 12995/1978, 11920/1981, and 44638/1982; and Japanese Patent Publication Nos. 4126/1980 and 4790/1980. However, the phosphoric ester compounds described in these patents are not necessarily satisfactory in the water resistance of the adhesive strength.